Familiarize yourself with your lawn mower. Read the owner's manual for operating instructions to ensure you operate the machine safely. Set the blade height to a middle setting -- between 1 and 2 inches. Grass cut too short will burn and grass that's too long makes it hard to cut the next time, according to All About Lawns.
Push the mower across the turf in a straight line from one end of the grass to the other. Once you're at the other side of the lawn, rotate the machine into the opposite direction and push it alongside the cut grass down a new row. Cutting the grass row by row will ensure uniform cutting over the entire lawn.
Empty the grass clippings from the attached bag once it's filled up into a trash can. Read the manufacturer instructions for removing and replacing the bag. Emptying the bag will prevent clumps of cut grass from falling all over a freshly trimmed lawn as you move up and down the rows.
Schedule the lawn trimmings once a week to maintain the look and strength of the grass -- cutting new growth regularly will encourage the grass to continue to grow thick and lush.